Two days ago, I notice a pimple-like red bump on my armpit. It Painful red bump under arm?

Two days ago, I noticed a pimple-like red bump on my armpit. It hurt rather, but I thought it was just an ingrown curls. Today the bump is smaller, but there is a red area that feel like a bruise running from the bump, down my arm halfway to my elbow. Is this an infection? I don't enjoy any other symptoms, but I'm concerned.Answers:
staph infection maybe?
well if it's just a red bump then i would say-so that theres nothing to worry something like because it happens to me all the time surrounded by my inner thigh area. It's because of sweat and skin rubbing together. But if it's more than just a boil i would suggest you see a doctor.
Well I suggest the best solution is to consult a doctor. It might not be something serious, but you'll never know if you don't walk to the doctor. When I was in the fifth position, I had a huge brown spot on the back of my thigh. My parents took me to the doctor, turns ou it be just a bug's bite.